1. Field of the Invention
This invention relates to a process for the removal of sulfur from a normally liquid hydrocarbonaceous oil, particularly from a sulfur-containing naphtha fraction. More particularly, the invention relates to a desulfurization process in which the hydrocarbonaceous oil is separated into several fractions and wherein each fraction is subjected to a separate desulfurization stage. The intermediate fraction is desulfurized by a sodium treatment.
2. Description of the Prior Art
It is known to desulfurize hydrocarbonaceous oils by separating the oil into various fractions and subjecting the fractions individually to desulfurization processes in separate reaction systems, see for example, U.S. Pat. No. 3,893,909 and U.S. Pat. No. 3,440,164.
U.S. Pat. No. 2,772,211 discloses treatment of hydrocarbon stocks and petroleum distillates including catalytically cracked napththa fractions with sodium used in an amount of 0.25 to 0.5 weight percent sodium based on feedstock, that is, less than a stoichiometric amount of sodium relative to the sulfur in the fraction.
U.S. Pat. No. 1,938,670 discloses the use of sodium or potassium to desulfurize gasoline or kerosene or other petroleum distillates. The alkali metal is employed in a proportion equal to or exceeding the atomic equivalent of sulfur present. An inert gas such as hydrogen or nitrogen increases the effectiveness of sulfur removal. See also U.S. Pat. No. 1,938,672.
U.S. Pat. No. 3,004,912 discloses desulfurization of diesel oil using sodium with or without the presence of hydrogen. The sodium is used in the proportion of 1 gram atom of sodium for 1 gram atom of sulfur in the feed, that is, sodium is used in less than the stoichiometric amount required for removal of sulfur as Na.sub.2 S.
U.S. Pat. No. 3,787,315 discloses the desulfurization of petroleum oil stocks by contact with sodium in the presence of hydrogen followed by water treatment of the sodium salt/oil sludge.
It has now been found that a desulfurization process in which naphtha is separated into fractions which are then individually desulfurized by different desulfurization processes offers advantages that will become apparent in the ensuing description.